************************************************************* GVP/USGS Weekly Volcanic Activity Report 31 May - 6 June 2006 ************************************************************* From: Gari Mayberry <mayberry@xxxxxxxxxxxxxx> GVP/USGS Weekly Volcanic Activity Report 31 May- 6 June 2006 Written by Sally Kuhn http://www.volcano.si.edu/reports/usgs/ New Activity/Unrest: | Ubinas, Perú Ongoing Activity: | Bulusan, Philippines | Karthala, Comoros Islands | Karymsky, Russia | Kilauea, USA | Merapi, Indonesia | Sakura-jima, Japan | Semeru, Indonesia | Soufriere Hills, Montserrat | St. Helens, USA | Tungurahua, Ecuador | Ulawun, Papua New Guinea New Activity/Unrest UBINAS Perú 16.355°S, 70.903°W; summit elev. 5,672 m On 3 June, the Alert Level for Ubinas was increased to Orange due to heightened explosive activity. During 31 May to 5 June, ash plumes reached altitudes of 7.9 km (26,000 ft) a.s.l. and drifted N, NE, SE, and S. According to a news report, on 5 June, officials in S Peru prepared to evacuate approximately 480 families. Geological Summary. A small, 1.2-km-wide caldera that cuts the top of Ubinas, Peru's most active volcano, gives it a truncated appearance. Ubinas is the northernmost of three young volcanoes located along a regional structural lineament about 50 km behind the main volcanic front of Peru. The upper slopes of the stratovolcano, composed primarily of Pleistocene andesitic lava flows, steepen to nearly 45 degrees. The steep-walled, 150-m-deep summit caldera contains an ash cone with a 500-m-wide funnel-shaped vent that is 200 m deep. Debris-avalanche deposits from the collapse of the SE flank of Ubinas extend 10 km from the volcano. Widespread plinian pumice-fall deposits from Ubinas include some of Holocene age. Holocene lava flows are visible on the volcano's flanks, but historical activity, documented since the 16th century, has consisted of intermittent minor explosive eruptions. Sources: Buenos Aires Volcanic Ash Advisory Center http://www.bom.gov.au/products/Volc_ash_recent.shtml, Dominican Today http://www.dominicantoday.com/app/article.aspx?id=14193 Ubinas Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1504-02 Ongoing Activity BULUSAN Luzon, Philippines 12.770°N, 124.05°E; summit elev. 1,565 m PHIVOLCS reported that an ash-and-steam cloud emitted from Bulusan on 31 May reached a height of 1.5 km above the summit (10,100 ft a.s.l.). Light ashfall, from trace amounts to 1.5 mm thickness, fell in areas W and NW of the volcano. Bulusan remained at Alert Level 1, with a Permanent Danger Zone of 4 km around the summit. Geologic Summary. Luzon's southernmost volcano, Bulusan, was constructed within the 11-km-diameter dacitic Irosin caldera, which was formed more than 36,000 years ago. A broad, flat moat is located below the prominent SW caldera rim; the NE rim is buried by the andesitic Bulusan complex. Bulusan is flanked by several other large intracaldera lava domes and cones, including the prominent Mount Jormajan lava dome on the SW flank and Sharp Peak to the NE. The summit of Bulusan volcano is unvegetated and contains a 300-m wide, 50-m-deep crater. Three small craters are located on the SE flank. Many moderate explosive eruptions have been recorded at Bulusan since the mid-19th century. Sources: Philippine Institute of Volcanology and Seismology http://www.phivolcs.dost.gov.ph/news/bulusan_bul_31May2006.html, The Manila Times http://www.abs-cbnnews.com/storypage.aspx?StoryId=40565 Bulusan Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0703-01= KARTHALA Comoros Islands, Indian Ocean 11.75°N, 43.38°E; summit elev. 2,361 m According to news articles, eruptive activity at Karthala that occurred on 28 May had ceased. No seismic activity was detected during 31 May to 1 June. Geologic Summary. The southernmost and largest of the two shield volcanoes forming Grand Comore Island (also known as Ngazidja), Karthala contains a 3 x 4 km summit caldera generated by repeated collapse. Elongated rift zones extend to the NNW and SE from the summit of the Hawaiian-style shield, which has an asymmetrical profile that is steeper to the S. Historical eruptions have modified the morphology of the compound, irregular summit caldera. More than twenty eruptions have been recorded since the 19th century from both summit and flank vents. Many lava flows have reached the sea on both sides of the island, including during many 19th-century eruptions from the summit caldera and vents on the northern and southern flanks. Sources: AFP http://news.yahoo.com/s/afp/20060601/sc_afp/comorosvolcano_060601150216, Reuters http://www.alertnet.org/thenews/newsdesk/B590859.htm Karthala Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0303-01= KARYMSKY Kamchatka Peninsula, Russia 54.05°N, 159.43°E; summit elev. 1,536 m During 27 May to 2 June, ash explosions from the summit of Karymsky continued. A large thermal anomaly in the crater was observed during 27-31 May. KVERT warned that activity from the volcano could affect nearby low-flying aircraft. Karymsky remained at Concern Color Code Orange <http://www.avo.alaska.edu/color_codes.php>. Geologic Summary. Karymsky, the most active volcano of Kamchatka's eastern volcanic zone, is a symmetrical stratovolcano constructed within a 5-km-wide caldera that formed about 7,600-7,700 radiocarbon years ago. Construction of the Karymsky stratovolcano began about 2,000 years later. The latest eruptive period began about 500 years ago, following a 2,300-year quiescence. Much of the cone is mantled by lava flows less than 200 years old. Historical eruptions have been Vulcanian or Vulcanian-Strombolian with moderate explosive activity and occasional lava flows from the summit crater. Most seismicity preceding Karymsky eruptions has originated beneath Akademia Nauk caldera, which is located immediately S of Karymsky volcano and erupted simultaneously with Karymsky in 1996. Source: Kamchatkan Volcanic Eruption Response Team http://www.kscnet.ru/ivs/kvert/updates.shtml Karymsky Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1000-13= KILAUEA Hawaii, USA 19.43°N, 155.29°W; summit elev. 1,222 m During 31 May to 5 June, lava from Kilauea continued to flow off of a lava delta into the ocean at the East Lae`apuki entry. Incandescence was visible from East Pond Vent, January Vent, Drainhole, and South Wall Complex when weather permitted observations. Incandescence high up on the PKK lava tube was observed on 4 June from the ground and by GOES satellite. Geologic Summary. Kilauea, one of five coalescing volcanoes that comprise the island of Hawaii, is one of the world's most active volcanoes. Eruptions at Kilauea originate primarily from the summit caldera or along one of the lengthy E and SW rift zones that extend from the caldera to the sea. About 90% of the surface of Kilauea is formed by lava flows less than about 1,100 years old; 70% of the volcano's surface is younger than 600 years. The latest Kilauea eruption began in January 1983 along the E rift zone. This long-term ongoing eruption from Pu`u `O`o-Kupaianaha has produced lava flows that have traveled 11-12 km from the vents to the sea, paving about 104 km2 of land on the S flank of Kilauea and building more than 200 hectares of new land. Source: US Geological Survey Hawaiian Volcano Observatory http://volcanoes.usgs.gov/update.html Kilauea information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1302-01- MERAPI central Java, Indonesia 7.542°S, 110.442°E; summit elev. 2,947 m The Alert Level at Merapi remained at 4, the highest level, during 31 May to 6 June. Sulfur-dioxide plumes were observed daily during this period and reached a height of 1.3 km above the summit (13,900 ft a.s.l.) on 1 June. According to the Darwin VAAC, low-level emissions were visible on satellite imagery on 1 and 6 June. Multiple pyroclastic flows reached a maximum distance of 4 km SE toward the Gendol River and 3.5 km SW toward the Krasak and Boyong Rivers. The Center of Volcanology and Geological Hazard Mitigation (CVGHM) reported on 31 May that lava avalanches moved towards the W for the first time during the recent eruption. According to a volcanologist in Yogyakarta, lava-flow distances and lava-dome volume had both approximately doubled since the 27 May M 6.2 earthquake. The lava-dome volume was estimated at 4 million cubic meters. On 6 June, groups living near the base of the volcano began to move into temporary shelters. Activities remain restricted within a 7 km radius from the volcano's summit and within 300 m of the banks of Krasak/Bebeng, Bedog, and Boyong Rivers to the SW, and Gendol River to the SE. Geologic Summary. Merapi, one of Indonesia's most active volcanoes, lies in one of the world's most densely populated areas and dominates the landscape immediately N of the major city of Yogyakarta. The steep-sided modern Merapi edifice, its upper part unvegetated due to frequent eruptive activity, was constructed to the SW of an arcuate scarp cutting the eroded older Batulawang volcano. Pyroclastic flows and lahars accompanying growth and collapse of the steep-sided active summit lava dome have devastated cultivated and inhabited lands on the volcano's western-to-southern flanks and caused many fatalities during historical time. The volcano is the object of extensive monitoring efforts by the Merapi Volcano Observatory of the Volcanological Survey of Indonesia. Sources: Center of Volcanology and Geological Hazard Mitigation (CVGHM) http://www.vsi.esdm.go.id/portal/html/index.php, Darwin Volcanic Ash Advisory Center http://www.bom.gov.au/products/IDD41290.shtml, AFP http://www.news24.com/News24/World/News/0,,2-10-1462_1945729,00.html, The Associated Press http://www.cnn.com/2006/WORLD/asiapcf/06/06/indonesia.volcano.ap/index.html Merapi Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0603-25= SAKURA-JIMA Kyushu, Japan 31.58°N, 130.67°E; summit elev. 1,117 m On 4 and 5 June, intermittent eruptions at Sakura-jima, from an upper E flank near or within the 1946 vent, produced ash clouds that reached unknown heights. No ash was visible on satellite imagery. This was the first reported Sakura-jima eruption from a vent outside the summit crater in 58 years. The 1946 vent was the source of major lava flows that reached the E and S coasts of the island. Geologic Summary. Sakura-jima, one of Japan's most active volcanoes, is a post-caldera cone of the Aira caldera at the northern half of Kagoshima Bay. Eruption of the voluminous Ito pyroclastic flow was associated with the formation of the 17 x 23-km-wide Aira caldera about 22,000 years ago. The construction of Sakura-jima began about 13,000 years ago and built an island that was finally joined to the Osumi Peninsula during the major explosive and effusive eruption of 1914. Activity at the Kita-dake summit cone ended about 4,850 years ago, after which eruptions took place at Minami-dake. Frequent historical eruptions, recorded since the 8th century, have deposited ash on Kagoshima, one of Kyushu's largest cities, located across Kagoshima Bay only 8 km from the summit. The largest historical eruption took place during 1471-76. Sources: Reuters http://www.sabcnews.com/world/asia1pacific/0,2172,128836,00.html, Hayakawa Yukio, Gunma University Sakura-jima Information from the Global Volcanism Program http://www.volcano.si.edu/gvp/world/volcano.cfm?vnum=0802-08= SEMERU Java, Indonesia 8.11°S, 112.92°E; summit elev. 3,676 m According to the Darwin VAAC, a pilot reported multiple minor eruptions from Semeru on 4 June. Small ash plumes were detected on satellite imagery on 5-6 June. Geologic Summary. Semeru is the highest volcano on Java and one of its most active. The symmetrical stratovolcano rises abruptly to 3,676 m above coastal plains to the S and lies at the southern end of a volcanic massif extending N to the Tengger caldera. Semeru has been in almost continuous eruption since 1967. Frequent small-to-moderate Vulcanian eruptions have accompanied intermittent lava dome extrusion, and periodic pyroclastic flows and lahars have damaged villages below the volcano. A major secondary lahar on 14 May 1981 caused more than 250 deaths and damaged 16 villages. Source: Darwin Volcanic Ash Advisory Center http://www.bom.gov.au/info/vaac/advisories.shtml Semeru Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0603-30= SOUFRIÈRE HILLS Montserrat, West Indies 16.72°N, 62.18°W; summit elev. 1,052 m During 26 May to 2 June, the Soufrière Hills lava dome continued to grow at a high rate of 10 cubic meters per second (average growth rate during January-April was 6 cubic meters per second). Numerous rockfalls and vigorous ash venting occurred from a vent to the W of the lava dome. A pilot reported that a small ash plume extended NW on 31 May. Ash plumes extending W and NW were visible on satellite imagery during 1-5 June and reached a maximum altitude of 2.7 km (9,000 ft) a.s.l. on 3 and 5 June. An ash plume on 4 June extended N of Puerto Rico. Geologic Summary. The complex dominantly andesitic Soufrière Hills volcano occupies the southern half of the island of Montserrat. The summit area consists primarily of a series of lava domes emplaced along an ESE-trending zone. English's Crater, a 1-km-wide crater breached widely to the east, was formed during an eruption about 4000 years ago in which the summit collapsed, producing a large submarine debris avalanche. Block-and-ash flow and surge deposits associated with dome growth predominate in flank deposits at Soufrière Hills. Non-eruptive seismic swarms occurred at 30-year intervals in the 20th century, but with the exception of a 17th-century eruption that produced the Castle Peak lava dome, no historical eruptions were recorded on Montserrat until 1995. Long-term small-to-moderate ash eruptions beginning in that year were later accompanied by lava-dome growth and pyroclastic flows that forced evacuation of the southern half of the island and ultimately destroyed the capital city of Plymouth, causing major social and economic disruption. Sources: Montserrat Volcano Observatory http://www.mvo.ms/, Washington Volcanic Ash Advisory Center http://www.ssd.noaa.gov/VAAC/messages.html, Soufrière Hills Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1600-05= ST. HELENS Washington, USA 46.20°N, 122.18°W; summit elev. 2,549 m During 31 May to 6 June, seismic signals indicated the lava spine continued to grow inside the crater of Mount St. Helens and occasionally produced minor rockfalls. The volcano remained at Volcano Advisory (Alert Level 2); aviation color code Orange. Geologic Summary. Prior to 1980, Mount St. Helens formed a conical, youthful volcano sometimes known as the Fuji-san of America. During the 1980 eruption the upper 400 m of the summit was removed by slope failure, leaving a 2 x 3.5 km horseshoe-shaped crater now partially filled by a lava dome. Mount St. Helens was formed during nine eruptive periods beginning about 40-50,000 years ago, and has been the most active volcano in the Cascade Range during the Holocene. The modern edifice was constructed during the last 2,200 years, when the volcano produced basaltic as well as andesitic and dacitic products from summit and flank vents. Historical eruptions in the 19th century originated from the Goat Rocks area on the N flank, and were witnessed by early settlers. Source: US Geological Survey Cascades Volcano Observatory http://vulcan.wr.usgs.gov/Volcanoes/MSH/CurrentActivity/framework.html St. Helens Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1201-05- TUNGURAHUA Ecuador 1.47°S, 78.44°W; summit elev. 5,023 m During 3-5 June, small-to-moderate explosions at Tungurahua produced plumes composed of gas, steam, and small amounts of ash. On 5 June, light ashfall was reported in areas on the SW flank. Night-time incandescence was observed on 3 and 5 June. Geologic Summary. The steep-sided Tungurahua stratovolcano towers more than 3 km above its northern base. It sits ~140 km S of Quito, Ecuador's capital city, and is one of Ecuador's most active volcanoes. Historical eruptions have been restricted to the summit crater. They have been accompanied by strong explosions and sometimes by pyroclastic flows and lava flows that reached populated areas at the volcano's base. The last major eruption took place from 1916 to 1918, although minor activity continued until 1925. The latest eruption began in October 1999 and prompted temporary evacuation of the town of Baños on the N side of the volcano. Source: Instituto Geofísico-Escuela Poltecnica Nacional http://www.igepn.edu.ec/vulcanologia/tungurahua/actividad/informet.htm, Tungurahua Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=1502-08= ULAWUN New Britain Island, Papua New Guinea 5.04°S, 151.34°E; summit elev. 2,334 m On 31 May, a thin steam-and-ash plume from Ulawun reached an altitude of below 3 km (10,000 ft) a.s.l. Geologic Summary. The symmetrical basaltic to andesitic Ulawun stratovolcano is the highest volcano of the Bismarck arc, and one of Papua New Guinea's most frequently active. Ulawun rises above the N coast of New Britain opposite Bamus volcano. The upper 1,000 m of the 2,334-m-high volcano is unvegetated. A steep-walled valley cuts the NW side of the volcano, and a flank lava-flow complex lies to the S of this valley. Historical eruptions date back to the beginning of the 18th century. Twentieth-century eruptions were mildly explosive until 1967, but after 1970 several larger eruptions produced lava flows and basaltic pyroclastic flows, greatly modifying the summit crater. Source: Darwin Volcanic Ash Advisory Center http://www.bom.gov.au/products/IDD41305.shtml Ulawun Information from the Global Volcanism Program http://www.volcano.si.edu/world/volcano.cfm?vnum=0502-12= ============================================================== To unsubscribe from the volcano list, send the message: signoff volcano to: listserv@xxxxxxx, or write to: volcano-request@xxxxxxxx To contribute to the volcano list, send your message to: volcano@xxxxxxxx Please do not send attachments. ==============================================================
